Our time period is from 0:00 to 16:00 London Time, Monday through Thursday and from 0:00 to 15:00 London Time, for Friday. However, low volume periods appear to be higher risk, and we would advise traders to use caution during these trading periods.

In'Mathematics of Money Management: Risk Analysis Techniques for Traders' it says "The difference between a negative expectation and a positive one is the difference between life and death ... So before money management can even be considered, you must have a positive Expectancy...".
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